Vector 3 reading low

Hi everyone,

I bought two Vector 3 dual sided power meters three months ago. They worked fine for a while but suddenly the wattage readings were lower for the same workout intensity. First I thought I was tired or overtrained but the difference was large, around 50 watts. On March 13th I did the 20' FTP test and I got 337 W. I did the same test today and despite being 5" faster, I got a wattage reading of 295 W. Both tests were at the same segment, a 5% hill, and wind and temperature were similar. Firmware is updated at 3.8 version and pedals are calibrated using a Garmin Edge 830 head unit on daily basis. You can see both activities here:

https://connect.garmin.com/modern/activity/6422799970

https://connect.garmin.com/modern/activity/6918090739

I've been searching on forums for some other users having the same problem as me but I couldn't find anything so I would appreciate some enlightenment.

Thank you very much.

0 Luko79 over 3 years ago

What was your bodyweight during the 2 efforts? Totally same? Or did You lose a few kgs since March? Tighten the pedals well again at 40NM, remove the batteries, put them back, do a few sprints, do manual calibration and test again.

0 josepjaipur over 3 years ago in reply to Luko79

Hi,

Thank you for your reply. Yes, my weight hasn't changed in more than a year, so it wasn't a factor. I will do tomorrow what you suggest and I will let you know, but I have already tried all of it except tightening the pedals.

0 Luko79 over 3 years ago in reply to josepjaipur

Hi Josep,

i checked your both rides on Strava more detailly and did some math: the latest ride, if your weight was 76 (net body) +13 (bike + bidons + clothes + accessories ), is totally correct, the watts are accurate. the march ride: if the total weight was the same as above, then the Vector overmeasured the power there with 30-40w (or with 10-13%, variable difference so something is weird there, the difference is not constant) , maybe it was (one of ) the 1st ride after the installation and the pedals werent properly zeroed/calibrated/set and the measuring was false.

if the above written weights are not correct, pls inform me what is it and i will refine my math

0 josepjaipur over 3 years ago in reply to Luko79

HI Luko,

thank you again for your reply. Those pedals were installed on March 8th and I did 15 workouts with similar wattage level readings. Then on March 27th I began to get low readings compared to the previous ones, and VO2Max and FTP were decreasing, from 62 and 315W all the way to 52 and 265W. Now, I have recovered somehow and they are 55 and 279W, respectively. Regarding the weight, I would say it is a bit lower, maybe 76+11 kg because I try to go light for those tests, but I don't think that this weight difference will be a factor.

I will find a way to adjust the pedals to 40NM and I will let you know if it changes anything.

0 Rafa over 3 years ago in reply to josepjaipur

Hola, lo has podido solucionar? A mi me miden como un 10% menos aproximadamente, hoy les he hecho el mantenimiento. Mañana los volveré a probar a ver.